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At least 217 records · Page 12Linked to original sources
PubMed2006

Lymph node hemophagocytosis in rickettsial diseases: a pathogenetic role for CD8 T lymphocytes in human monocytic ehrlichiosis (HME)?

BACKGROUND: Human monocytic ehrlichiosis (HME) and Rocky Mountain spotted fever (RMSF) are caused by Ehrlichia chaffeensis and Rickettsia rickettsii, respectively. The pathogenesis of RMSF relates to rickettsia-mediated vascular injury, but it is unclear in HME. METHODS: To study histopathologic responses in the lymphatic system for correlates of immune injury, lymph nodes from patients with HME (n = 6) and RMSF (n = 5) were examined. H&E-stained lymph node tissues were examined for five histopathologic features, including hemophagocytosis, cellularity, necrosis, and vascular congestion and edema. The relative proportions of CD68 macrophages, CD8 and CD4 T lymphocytes, and CD20 B lymphocytes were evaluated by immunohistochemical staining. RESULTS: Hemophagocytosis was similar in HME and RMSF, and was greater than in control cases (p = .015). Cellularity in HME was not different from controls, whereas RMSF lymph nodes were markedly less cellular (p < 0.002). E. chaffeensis-infected mononuclear phagocytes were infrequent compared to R. rickettsii-infected endothelial cells. More CD8 cells in lymph nodes were observed with HME (p < .001), but no quantitative differences in CD4 lymphocytes, macrophages, or B lymphocytes were identified. CONCLUSION: Hemophagocytosis, CD8 T cell expansion, and the paucity of infected cells in HME, suggest that E. chaffeensis infection leads to macrophage activation and immune-mediated injury.

Adolescent↗
PubMed2006

Rickettsial diseases in Russia.

Currently, several rickettsioses are officially being reported in the Russian Federation. These are epidemic typhus and Brill-Zinsser disease, both caused by Rickettsia prowazekii which has a historic prevalence in Russia. Nowadays only single sporadic cases of R. prowazekii infection are reported. The last significant outbreak occurred in 1997 in a mental nursing home, where 29 cases were identified. Registered morbidity of typhus in Russia varies from 0 to 0.01 per thousand for the last decade. Siberian tick typhus, caused by R. sibirica, is registered on a large territory from Pacific coasts to Western Siberia, and its incidence continuously increases, varying between 2.5 and 4.0 thousand officially registered cases per year. Astrakhan spotted fever, caused by R. conorii subsp. caspia has been recognized since 1983. Recently, Far Eastern tick-borne rickettsiosis, caused by R. heilongjiangensis, has been described. Several other pathogenic spotted fever group rickettsiae have been detected and isolated from ticks in Russia; however, they have not yet been linked with clinical cases in these regions.

Animals↗
PubMedDate not supplied

[Spotted fever group rickettsial disease in Argentinean travelers].

During 1996, four patients that returned from South Africa suffering from rickettsiosis were attended at the Traveler's Medicine practice of our hospital. All of them presented fever, headache and cutaneous scar. One of these presented maculopapular rash, while the rest developed a vesicular rash. The Weil-Felix reaction was negative and the immunofluorescence test for Rickettsia conorii was positive in all cases. None of the patients remembered having been bitten by any insects, however all of them had been staying in or going through a wild environment. All the patients were treated with doxycycline and presented a good outcome.

Adult↗